Preferred Instruments PCC-IV, Instruction Manual

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PCC-IV Instruction Manual (Rev. 0.1) Page 6-41 Section 6
– Blockware Functions
Technical Reference
Deadband or Hysteresis (Parameter 3): When Deadband (DB)= 0.0: Output = 1, if |(PV-SP)| > Deviation, or Output
= 0, if |(PV-SP)| =< Deviation. When Deadband > 0: Output = 1, if |(PV-SP)| > Deviation, and once the Output
becomes a 1, it remains a 1 until [|(PV-SP)| < (Deviation
– DB)] and then it resets to 0. See figure above.
Internal vs External Setpoint (Parameters 1 and 4, and Input 2): By default, Parameter 1 = 1, and
DEVALM uses
the EXT SP (External Setpoint) Input (Input 2) as the SP. Changing Parameter 1 to "2", causes DEVALM to use
the INTERNAL SETPOINT stored in Parameter 4 as the SP.
Alarm Time Delay (Parameter 7): |(PV-SP)| must be continuously greater than the % Deviation threshold for
(Parameter 7) seconds before the
DEVALM Block Output will change to a "1".
Alarm Disable (Parameter 5, and Input 3): By default,
DEVALM is Enabled and responds to alarms because the
defaults are: Input 2 is Block 2 ( D0 or Low), and Alarm Disable is ACTIVE HI (Parameter 5 = 1). However, Blockware
can use the Disable Input (Input 3) to selectively Disable individual alarm Blocks; that is, force the alarm Block
Output to be a "0". Parameter 5 determines if the Disable signal is "Active HI", or "Active LO" as follows:
Parameter 5 Disable Input Mode
1 (Active HI) 0 Enabled
1 (Active HI) 1 Disabled
0 (Active LO) 0 Disabled
0 (Active LO) 1 Enabled
Inverted Output (Parameter 6): When Parameter 6 = 1, The Block Output is opposite the normal value. Or, when
INVERTED = "1
”, Output = "1" if |(PV-SP)| < Deviation.
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NAME: DEVALM SINGLE USE FUNCTION: N OUTPUT TYPE: D
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Input Type Description Notes
_____________________________________________________________________________________________
1 A PV INPUT
2 A EXT SP INPUT 1
3 D DISABLE INPUT 2
Parameter Description Default Max Min Code Notes
_____________________________________________________________________________________________
1 SP MODE 1=EXT 2=INT 1 2 1 2 1
2 % DEVIATION THRESHOLD 2.00 199.99 0.10 1
3 % DEADBAND 0.10 100.00 0.00 1 3
4 % INT SP 50.00 199.99 -199.99 1 1
5 ALARM DISABLE ACTIVE LO/HI
0=LO, 1=HI 1 1 0 2 2
6 INVERT OUTPUT 0=NO 1=YES 0 1 0 2 5
7 ALARM DELAY SECONDS 0 600 0 1 4
Notes:
1. See "Internal vs External Setpoint" above.
2. See "Alarm Disable" above.
3. See "Deadband" above.
4. See "Alarm Time Delay" above.
5. See "Inverted Output" above